Porous materials such as, for example, fiber reinforced cement materials, gypsum wall board and the like, are increasingly being used as internal and external cladding panels in a variety of building construction applications. These porous materials have good fire resistance and barrier characteristics, and may be produced at a reasonable cost.
Fiber-reinforced cement materials may be manufactured by applying a finish to one or more surfaces of the panel. The finish may be a coating that prevents or reduces water penetration into porous surfaces of the panel. The coating is typically applied to a surface of the fibrous cement material in a liquid state, but subsequently undergoes a chemical transformation to a solid-like cured state. Two-part reactive systems, for example two-part epoxy resins that form a reactive mixture upon combining a base component with an epoxy component, have been used as coatings for fiber reinforced cement materials.
It is particularly desirable to apply the coating to at least the exterior face and edges of the fibrous cement panel to prevent water penetration and/or provide improved adhesion to additional protective and decorative coatings. Various coating methods, for example, spray coating and sponge-roll coating, have been used for applying coatings to the surfaces of fiber reinforced cement materials.
Unfortunately, multi-part reactive coating systems, such as two-part epoxy resins, have a limited pot life. After the components are combined to initiate the curing reaction and form a reactive mixture, if the mixture is not applied to a substrate within a relatively short period of time the mixture must be discarded. This wastes coating materials and requires extensive coater down time to clean the coating fluid delivery system, particularly if a coating line stoppage occurs. In addition, once the materials are mixed and the curing reaction begins, the properties of the mixture are constantly changing, so control of process variables in the coating process may be difficult.